Medication delivery pen

ABSTRACT

A medication delivery pen is provided including a leadscrew having a plurality of threads; a driver coaxially disposed about at least a portion of the leadscrew; a dosing ring non-rotatably disposed on the driver, the dosing ring also being slidable along the driver; and, a dose knob coaxially disposed about the dosing ring. At least one tooth is formed on one of the dose knob and the dosing ring, and at least one groove is formed on the other of the dose knob and the dosing ring, with the groove being formed to receive the tooth. The dosing ring is selectively movable relative to the dose knob from a first position where the tooth and the groove are spaced apart to a second position where the tooth is received within the groove, the dosing ring being rotatable with the dose knob with the dosing ring being in the second position. Incorrect dosage settings of the inventive pen may be easily corrected by a user via a novel dial-back feature that enables the user to reset the dose amount without expelling medication and without having to dial the dose knob to an extended, reset position.

BACKGROUND OF THE INVENTION

[0001] This invention relates to medication delivery instruments and,more particularly, to medication delivery pens, such as those used inadministering insulin.

[0002] Various medication delivery pen designs are known in the priorart, including that shown in U.S. Pat. No. 6,248,095, which issued onJun. 19, 2001, to one of the inventors herein and the assignee hereto.To administer a dose of medication, such as insulin, using the pen ofU.S. Pat. No. 6,248,095, and as is commonly done with other medicationdelivery pen designs, a dose knob is manually rotated until a desireddose amount is set. Thereafter, a needle cannula is inserted into apatient and a button located at the end of the dose knob is depressedresulting in the administration of the desired dose. U.S. Pat. No.6,248,095 is incorporated herein by reference in its entirety.

[0003] Prior art medication delivery pens, however, suffer from thedrawback that if the dose knob is adjusted beyond a desired dose (i.e.,an error in dosing is made), a waste of time or medication results incorrecting to the desired amount. In one manner of correcting for themistake, the dose knob can be “dialed back” to the lower dose amount andthere set. However, such “dialing back” will result in the wastefulexpulsion of medicine commensurate to the amount corrected. For example,if the pen is “dialed back” from a 300 μl dosage to a 250 μl dosage, 50μl will be wastefully expelled. Alternatively, some pens, such as thatdisclosed in U.S. Pat. No. 6,248,095, provide for a reset mechanismwhich allows for the dose knob to be disengaged and returned to a zeroposition without “dialing back”. Such reset typically involves “dialingout” the dose knob to its fullest extent where it is disengaged and thenreturning the dose knob back to a start position. Although it ispossible to reset the pen, additional time and effort is required to doso.

SUMMARY OF THE INVENTION

[0004] The present invention provides a medication delivery pen whichovercomes the deficiencies of the prior art. The medication delivery penincludes a leadscrew having a plurality of threads; a driver coaxiallydisposed about at least a portion of the leadscrew; a dosing ringnon-rotatably disposed on the driver, the dosing ring also beingslidable along the driver; and, a dose knob coaxially disposed about thedosing ring. At least one tooth is formed on one of the dose knob andthe dosing ring, and at least one groove is formed on the other of thedose knob and the dosing ring, with the groove being formed to receivethe tooth. The dosing ring is selectively movable relative to the doseknob from a first position where the tooth and the groove are spacedapart to a second position where the tooth is received within thegroove, the dosing ring and the dose knob being rotatable with thedosing ring in the second position.

[0005] With the subject invention, the dose knob can be dialed freely inboth directions, without causing medicine to be administered,particularly upon “dialing back”. In addition, resetting of the doseknob is altogether avoided in allowing for a downward-correction indosage amount.

[0006] These and other features of the subject invention will be betterunderstood through a study of the following detailed description andaccompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a side-elevational view of a medication delivery penconstructed in accordance with the subject invention;

[0008]FIG. 2 is an exploded view of a medication delivery penconstructed in accordance with the subject invention;

[0009]FIG. 3 is a cross-sectional view of a body useable with thesubject invention;

[0010]FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3;

[0011]FIG. 5 is a cross-sectional view of a driver useable with thesubject invention;

[0012]FIG. 6 is an enlarged perspective view of a proximal end of thedriver shown in FIG. 5;

[0013]FIG. 7 is a cross-section of a medication delivery pen constructedin accordance with the subject invention;

[0014]FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 7;

[0015]FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 7;

[0016]FIG. 10 is a cross-sectional view taken along line 10-10 of FIG.7; and,

[0017]FIGS. 11 and 12 are partial cross-sectional views showing,respectively, the medication delivery pen in a rest state and in aninitial dosing state.

DETAILED DESCRIPTION OF THE INVENTION

[0018] With reference to the Figures, particularly FIG. 1, a medicationdelivery pen is shown and generally designated with the referencenumeral 10. The medication delivery pen 10 may be used for theadministration of various medications, including insulin; the medicationnot comprising a part of the present invention. In addition, the term“medication” is used in an illustrative and non-limiting manner to referto any substance that may be injected into a patient for any purpose.The medication delivery pen 10 of the present invention may also bereusable or disposable.

[0019] With reference to FIG. 2, the medication delivery pen 10generally includes a cap 12, a cartridge holder 14, a spinner 16, a body18, a dose knob 20, a dosing ring 22, a driver 24, a leadscrew 26, adosing ring adaptor 28, and a thumb button 30. The cartridge holder 14is formed to accommodate a drug cartridge 32, which may be of anyconventional design. By way of non-limiting example, the drug cartridge32 may include an elastomeric septum 34 at a proximal end thereof and anopen distal end 36 which exposes a slidable plunger 38 (FIG. 7). Drugmedication is contained within the drug cartridge 32 between the septum34 and the plunger 38. As will be described in more detail below, thespinner 16 is configured to engage the plunger 38 and force forwardmovement thereof in expelling drug from the drug cartridge 32. A needle(not shown) is required to administer drug from the medication deliverypen 10. The needle may be a double-ended cannula which is threadedlymounted onto threads 40 of the cartridge holder 14. One end of thecannula is exposed for insertion into a patient, while the second end ofthe cannula is disposed to pierce the septum 34 of the drug cartridge32. After administration of the dose, the needle is removed, with theseptum 34 self-sealing. The cap 12 is formed to releasably mount ontothe cartridge holder 14, such as with a snap fit, to limit contaminationof the septum 34 and the surrounding portions of the cartridge holder14. A resilient holding arm 13 may extend from the cap 12 to provideholding force for the pen 10 in a patient's pocket. One or more windows35 may also be provided in the cartridge holder 14 to give a visualindication of the drug level in the drug cartridge 32.

[0020] With reference to FIG. 3, the body 18 is generally cylindrical,having threads or detents 42 onto which the cartridge holder 14 isformed to be mounted. A bulkhead 44 extends across the interior of thebody 18 through which an aperture 46 is formed. The aperture 46 isdefined to allow the passage therethrough of the leadscrew 26, yet theaperture 46 is shaped (e.g., being rectangular) to prevent rotation ofthe leadscrew 26 therewithin. The body 18 also includes aninteriorly-supported cylindrical wall 48 which defines a channel 50therethrough. A transverse recess 53 is defined between the aperture 46and the channel 50 which is bounded by wall 55, that may be continuousor discontinuous. In addition, a dose setting thread 54, as known in theprior art, is formed on the interior of the body 18, along with a window56 for dosage selection. A pointer 58 defined on the body 18 may extendinto the window 56 to clearly point out a selected dosage level.

[0021] With reference to FIG. 5, the driver 24 includes proximal anddistal ends 60 and 62, respectively, with a snap ring 64 being formed atthe proximal end 60. The snap ring 64 is formed to pass through thechannel 50 of the body 18 and lock onto the wall 48 in the recess 53(FIG. 7). With the snap ring connection, the driver 24 is fixed axiallyrelative to the body 18, yet is able to rotate relative thereto.Internal threads 68 are also provided to threadedly engage threads 70 ofthe leadscrew 26. Additionally, as shown in FIG. 2, ledge 72 and one ormore longitudinal keyways 74 are defined on the exterior surface of thedriver 24.

[0022] Preferably, as more clearly shown in FIG. 4, a plurality ofratchet teeth 52 extend from the cylindrical wall 48. In addition, oneor more ratchet fingers 66 are formed on the proximal end 60 of thedriver 24 and are located in proximity to the snap ring 64. The ratchetfingers 66 are positioned within the channel 50 when the driver 24 islocked in the recess 53 (FIG. 7). Preferably, the ratchet teeth 52 andthe ratchet fingers 66 cooperate to allow the driver 24 to rotate inonly one direction relative to the body 18. The ratchet teeth 52 and theratchet fingers 66 provide a measure of protection against unwantedrearward movement of the leadscrew 26, as described more fully below.

[0023] Dosing ring 22 is formed with one or more grooves 76 at aproximal end 78 thereof; a plurality of longitudinal ribs 80; a snapring 82 in proximity to a distal end 84 thereof; and, inwardly extendingsplines 86 formed and located to be disposed in the keyways 74 of thedriver 24. As best shown in FIG. 9, in assembling the pen 10, the dosingring 22 is mounted onto the driver 24 with the splines 86 extending intothe keyways 74. As a result, the dosing ring 22 cannot be rotatedrelative to the driver 24. However, the splines 86 are formed such toallow the dosing ring 22 to axially move along the length of the keyways74. Also, as shown in FIG. 9, the grooves 76 are preferably formed onthe proximal end 78 to face axially and are formed about the entireperiphery thereof, more preferably, at equal intervals. The grooves 76are separated by partitions 88, which may be rounded to facilitateengagement of the grooves 76 with the teeth of the dose knob 20described below.

[0024] The dose knob 20 is generally tubular having open proximal anddistal ends 90 and 92, respectively. A textured handle 94 is formed inproximity to the distal end 92 which is engageable by a user to rotatethe dose knob 20 in setting the pen 10 to a desired dosage amount. Thedose knob 20 includes one or more thread portions 95 (FIG. 11) formed tothreadedly engage the dose setting thread 54 of the body 18.Accordingly, the dose knob 20 may be rotated within the body 18resulting in translation of that rotation to axial displacement of thedose knob 20 relative to the body 18 in setting a desired dosage. Dosageindicia (not shown) may also be disposed externally of the dose knob 20.

[0025] The dose knob 20 preferably includes one or more ratchet arms 96formed to be biased inwardly. With reference to FIG. 8, with the doseknob 20 being coaxially disposed about the dosing ring 22, the ratchetarms 96 are aligned with the longitudinal ribs 80 so that rotation ofthe dose knob 20 relative to the dosing ring 22 results in the ratchetarms 96 acting against the ribs 80 in a ratcheting manner giving a useran audible signal of such rotation. In contrast to the prior art, thedose knob 20 can freely rotate in both directions relative to the dosingring 22 with the ratchet arms 96 acting against the ribs 80 during bothrotational directions of the dose knob 20.

[0026] The dose knob 20 is also formed with one or more lips 98 (FIG. 2)which are formed in proximity to the proximal end 90 and from whichextend one or more teeth 100. The teeth 100 are formed and positioned tobe received in the grooves 76 formed on the dose knob 20 and preferablyface axially with regard to the longitudinal axis of the dose knob 20.With reference to FIG. 10, the teeth 100 are much less in number thanthe grooves 76 to facilitate alignment.

[0027] The dosing ring 22 is mounted onto the dosing ring adaptor 28with the snap ring 82 of the dosing ring 22 snapping into lockingchannel 102 defined in the dosing ring adaptor 28. As such, the dosingring 22 and the dosing ring adaptor 28 are movable in concert with eachother. In an alternative embodiment, the dosing ring adaptor 28 and thedosing ring 22 may be formed unitarily.

[0028] The leadscrew 26 may be of any conventional type and is formedwith a threaded end 103. The spinner 16 includes a threaded aperture 105formed to threadedly engage the threaded end 103 in mounting the spinner16 onto the leadscrew 26. Alternatively, the thumb button 30 is of anyconventional design and formed to snap onto the dose ring adaptor 28.The thumb button 30 may be unitarily formed with the dose ring adaptor28.

[0029] With reference to FIGS. 7, 11 and 12, the dosing ring adaptor 28includes an inwardly extending shoulder 104. With the pen 10 being fullyassembled, a biasing means 106, such as a coil spring, is preferablydisposed between the ledge 72 of the driver 24 and the shoulder 104 ofthe dosing ring adaptor 28. Consequently, the dosing ring adaptor 28 isurged distally within the pen 10, along with the dosing ring 22. Stopmember 108 may be provided on the dosing ring adaptor 28 formed to abutagainst inwardly-extending ring 110 defined on the dose knob 20 underforce of the biasing means 106 to limit distal movement of the dosingring adaptor 28.

[0030] Referring to FIG. 11, in a rest state, the dosing ring 22 isurged into a rest position with the grooves 76 being spaced from theteeth 100 of the dose knob 20. Accordingly, the dose knob 20 can befreely rotated without rotating the dosing ring 22. In this manner, thedose knob 20 can be rotated within the body 18 (with rotational movementbeing translated into axial displacement) and set to a desired dosage ina manner similar to prior art devices. With the dose knob 20 thustranslating, the dosing ring adaptor 28, the biasing means 106 and thedosing ring 22 move therewith, while the dosing ring 22 remains in itsrest position. The dosing ring 22 slides axially long the driver 24 as aproper dose is selected. The subject invention, unlike the prior art,allows the dose knob 20 to be “dialed back” freely if a desired dosageamount is inadvertently by-passed, without the undesirable and costlyeffect of expelling medication.

[0031] In a preferred embodiment, with a desired dosage amount beingset, the ratchet arms 96 advantageously provide holding force tomaintain the desired radial position of the dose knob 20 relative to thedosing ring 22, and, thus, to the driver 24. In other words, the doseknob 20 cannot rotate without overcoming this holding force.

[0032] The needle cannula may be attached to the pen 10 prior to orafter setting the desired dosage, as a matter of user preference. Oncethe needle cannula has been prepared, attached to the cartridge holder14, and inserted into the patient, the thumb button 30 is depressed.Initially, the applied force will act against the biasing means 106causing initial straight-line motion of the dosing ring adaptor 28 andeventual interengagement of the grooves 76 and the teeth 100, as shownin FIG. 12. Additional force will cause the dose knob 20 to rotate indescending along the dose setting thread 54 in a proximal direction.With the interengagement of the grooves 76 and the teeth 100, the dosingring 22 rotates with the dose knob 20. In turn, the driver 24 rotateswith the dosing ring 22 (due to the interengagement of the keyways 74and the splines 86), and the threads 68 of the driver 24 rotate aboutthe threads 70 of the leadscrew 26. Since the leadscrew 26 cannot rotatebecause of its fixed positioning in the aperture 46, the leadscrew 26axially translates in a proximal direction to urge the spinner 16against the plunger 38 in expelling medication from the drug cartridge32. The volume of the drug to be expelled is calibrated to the settingsof the dose knob 20.

[0033] Once a dose has been administered, the thumb button 30 isreleased, causing the dosing ring 22 to return to its rest position. Thedose knob 20 can then be adjusted to a zero position ready for the nextdrug administration. The spinner 16 does not move in setting a dosageamount and, thus, is at a zero position after each dose administration.In the preferred embodiment, to maintain the spinner 16 positionaccurately, the interengagement of the ratchet teeth 52 and the ratchetfingers 66 prevents undesired rearward rotation of the driver 24 thatwould result in the leadscrew 26 possibly translating distally. Theadministration process is repeated until the drug cartridge 32 is spent.If the pen 10 is reusable, the cartridge can be replaced, whereas, ifthe pen is disposable, the entire pen 10 may be disposed of.

[0034] As will be appreciated by those skilled in the art, variousmodifications can be made with the spirit of the invention beingmaintained. For example, grooves may be formed on the dose knob andteeth on the dosing ring, or a combination thereof.

[0035] While the invention has been described in relation to thepreferred embodiments with several examples, it will be understood bythose skilled in the art that various changes may be made withoutdeviating from the spirit and scope of the invention as defined in theappended claims.

What is claimed is:
 1. A medication delivery pen for expellingmedication from a medicine cartridge, said pen comprising: a driver; adosing ring non-rotatably disposed on said driver and axially slidablethereon and therealong; and, a dose knob coaxially disposed about saiddosing ring, wherein at least one tooth is formed on one of said doseknob and said dosing ring, and wherein at least one groove is formed onthe other of said dose knob and said dosing ring, said tooth and saidgroove being formed for selective cooperative engagement with eachother; wherein said dosing ring is selectively movable axially relativeto said dose knob from a first position where said tooth and said grooveare spaced apart from each other, to a second position where said toothand said groove are cooperatively engaged with each other such that saiddosing ring is rotatable with said dose knob when said dosing ring is insaid second position.
 2. A pen as in claim 1, further comprising biasingmeans to urge said dosing ring into said first position.
 3. A pen as inclaim 2, wherein said biasing means is a coil spring.
 4. A pen as inclaim 1, wherein said second position is a medication delivery positionin which said pen is used to deliver medication.
 5. A pen as in claim 1,wherein said dosing ring having a plurality of longitudinal ribs, saiddose knob having at least one inwardly biased ratchet arm to resilientlyact against said ribs upon relative motion between said dosing ring andsaid dose knob.
 6. A pen as in claim 1, further comprising a bodycoaxially disposed about said dose knob, said dose knob threadedlyengaging said body.
 7. A pen as in claim 1, further comprising aleadscrew having a plurality of threads, where said driver is coaxiallydisposed about a portion of said leadscrew and includes internal threadsfor threadedly engaging said leadscrew.
 8. A pen as in claim 7, furthercomprising a body coaxially disposed about said dose knob, said bodyincluding an aperture through which said leadscrew passes, said aperturebeing formed to prevent rotation of said leadscrew relative to saidbody.
 9. A pen as in claim 1, further comprising a body coaxiallydisposed about said dose knob, said dose knob having an externallydefined thread portion, said body having an internally defined threadfor receiving said thread portion, said thread portion and said threadtranslating rotational movement into axial displacement when said doseknob is selectively rotated by a user.
 10. A pen as in claim 9, furthercomprising a cartridge holder within which the medicine cartridge may beprovided.
 11. A pen as in claim 10, wherein said cartridge holder isremovably secured to said body.
 12. A pen as in claim 10, wherein saidcartridge holder is fixedly secured to said body.
 13. A medicationdelivery pen for expelling medication from a medicine cartridge, themedicine cartridge having a pierceable septum sealing one end, a needlecannula being removably securable to the one end for piercing theseptum, said pen comprising: a leadscrew having a plurality of threads;a driver coaxially disposed about a portion of said leadscrew; a dosingring non-rotatably disposed on said driver and axially slidable thereonand therealong; a dose knob coaxially disposed about said dosing ringand selectively rotatable by a user, wherein said dose knob has a firstfeature defined thereon and said dosing ring has a second featuredefined thereon, said first and said second features being complementarywith each other and being selectively operatively engageable with eachother; said dosing ring being biased into a first position wherein saidfirst feature and said second feature are not operatively engaged witheach other, said dosing ring being selectively movable from said firstposition to a second position in which said first feature and saidsecond feature are operatively engaged with each other to lockinglyengage said dose knob and said dosing ring so as to allow medicine to beexpelled from the cartridge through the needle cannula.
 14. A pen as inclaim 13, further comprising a coil spring for biasing said dosing ringinto said first position.
 15. A pen as in claim 13, further comprising abody coaxially disposed about said dose knob, said dose knob having anexternally defined thread portion, said body having an internallydefined thread for receiving said thread portion, said thread portionand said thread translating rotational movement into axial displacementwhen said dose knob is selectively rotated by a user.
 16. A pen as inclaim 15, further comprising a cartridge holder within which themedicine cartridge may be provided.
 17. A pen as in claim 16, whereinsaid cartridge holder is removably secured to said body.
 18. A pen as inclaim 16, wherein said cartridge holder is fixedly secured to said body.